Which two muscles combine to form the reciprocal apparatus?

Which two muscles combine to form the reciprocal apparatus?

• A. Peroneus tertius and DDF
• B. SDF and DDF
• C. Vastus medialis and Rectus femoris
• D. Peroneus tertius and SDF

Answer: (D)

In the hind limb, the reciprocal apparatus is a tendinous linkage that coordinates movement between the stifle and the hock, allowing them to move in harmony rather than independently. This coordination is achieved by the peroneus tertius tendon and the superficial digital flexor tendon, which run together and influence both joints. When the stifle flexes or extends, these two tendons transmit that motion to the hock, helping to lock the limb in a standing position as part of the stay apparatus. The deep digital flexor tendon isn’t part of this specific linkage, and the quadriceps muscles (like vastus medialis and rectus femoris) control knee extension rather than forming the reciprocal mechanism.

In the hind limb, the reciprocal apparatus is a tendinous linkage that coordinates movement between the stifle and the hock, allowing them to move in harmony rather than independently. This coordination is achieved by the peroneus tertius tendon and the superficial digital flexor tendon, which run together and influence both joints. When the stifle flexes or extends, these two tendons transmit that motion to the hock, helping to lock the limb in a standing position as part of the stay apparatus. The deep digital flexor tendon isn’t part of this specific linkage, and the quadriceps muscles (like vastus medialis and rectus femoris) control knee extension rather than forming the reciprocal mechanism.